Today yet another tester asked “When a client asks ‘How long will the testing take for our development project?’, how should I reply?” The simplest answer I can offer is this: if you’re testing as part of a development project, testing will take exactly as long as development will take. That’s because effective, efficient testing is not separate from development; it is woven into development. When we develop a software … Read more
When a decision maker asks “When will testing be done?”, in my experience, she really means is “When will I have enough information about the state of the product and the project, such that I can decide to release or deploy the product?” There are a couple of problems with the latter question. First, as Cem Kaner puts it, “testing is an empirical, technical investigation of the product, done on … Read more
My colleague and friend Eric Jacobson, who recently (as I write) did a bang-up job on his first conference presentation at STAR West 2011, asks a question in response to this blog post from 2006. (I like it when people reflect on an issue for a few years.) Eric asks: You are suggesting it may not make sense for testers to give time-based estimates to their teams, but what about … Read more
In this series of blog posts, I’ve been talking about project estimation. But I’m a tester, and if you’re reading this blog, presumably you’re a tester too, or at least you’re interested in testing. So, all this has might have been interesting for project estimation in general, but what are the implications for test project estimation? Let’s start with the tester’s approach: question the question. Is there ever such a … Read more
Over the last few posts, exploratory automation has suggested some interesting things about project dynamics and estimation. What might we learn from these little mathematical experiments? The first thing we need to do is to emphasize the fact that we’re playing with numbers here. This exercise can’t offer any real construct validity, since an arbitrary chunk of time combined with a roll of the dice doesn’t match software development in … Read more
Last time out, we determined that mucking with the estimate to account for variance and surprises in projects is in several ways wanting. This time, we’ll make some choices about the tasks and the projects, and see where those choices might take us. Leave Problem Tasks Incomplete; Accept Missing Features There are a couple of variations on this strategy. The first is to Blow The Whistle At 100. That is, … Read more
In the last post, I talked about the asymmetry of unexpected events and the attendant problems with estimation. Today we’re going to look at some possible workarounds for the problems. Testers often start by questioning the validity of models, so let’s start there. The linear model that I’ve proposed doesn’t match reality in several ways, and so far I haven’t been very explicit about them. Here are just a few … Read more
There has been a flurry of discussion about estimation on the net in the last few months. All this reminded me to post the results of some number-crunching experiments that I started to do back in November 2009, based on a thought experiment by James Bach. That work coincided with the writing of Swan Song, a Better Software column in which I discussed The Black Swan, by Nassim Nicholas Taleb. … Read more
John D. Cook recently issued a blog post, How many errors are left to find?, in which he introduces yet another silly quantitative model for estimating the number of bugs left in a program. The Lincoln Index, as Mr. Cook refers to it here, was used as a model for evaluating typographical errors, and was based on a method for estimating the population of a given species of animal. There … Read more
Yesterday I set up a thought experiment in which we divided our day of testing into three 90-minute sessions. I also made a simplifying assumption that bursts of testing activity representing some equivalent amount of test coverage (I called it a micro-session, or just a “test”) take two minutes. Investigating and reporting a bug that we find costs an additional eight minutes, so a test on its own would take … Read more